I have been enjoying Jonathan Lear's "Aristotle: The Desire to Understand" so much more than when I was attempting to read Aristotle's original texts in translation, that I think I shall do the same with Aquinas; that is, reading Brian Davies's "The Thought of Thomas Aquinas" instead of Aquinas' original writings.
Why should I spend a decade reading the Summa Theologica, once through, with little understanding, when I can read Davies's work and gain immediate understanding, within a few months? I will not be able to say, "I read Aquinas." However, I will be able to understand his ideas and start contemplating them. With this goal in mind, reading Davies's work seems to be a reasonable approach.
And I can always go to the primary sources afterwards. Once I finish reading Lear and Davies, a logical next step would be Irwin and Fine's "Aristotle: Selections" and McDermott's "Summa Theologica: A Concise Translation".
It's the ideas that are important to me – to be able to take these great ideas and consider how to apply them to life. My goal is not to be an Aquinas/Aristotle scholar – to be one would need a vast quantity of time which I do not have.